A testing device of this type for the container of an emergency respirator has become known from EP-B1,128,142. The prior-art testing device consists of an oval test button with a cylindrical plunger made in one piece with it, which is guided in a supporting device connected to the container. The container is closed with a door and a locking device that can be actuated. In the place of the test button, the door has a corresponding oval cutout, through which the test button can be pulled forward to the outside. In normal operation, the test button is located within the cutout and is flush with the door. When the locking device is actuated, the door is released and is freely pivotable around a hinge located on the container. During test operation, the test button is first pulled forward and, rotated by 90.degree., it is brought into a testing position. The oval contour of the test button is now at right angles to that of the cutout. When the locking device is actuated, the pivoting stroke of the door is limited by the projecting test button rotated by 90.degree.. Accessory equipment, e.g., emergency respirators, which may be located in the container, are thus retained, and the door can again be locked after being pressed onto the container.
It is disadvantageous that an expensive supporting device for the testing device is necessary on the container, and the test button must be adjusted, together with the supporting device, such that it will be flush with the cutout in the door in normal operation. This makes inexpensive manufacture difficult.